Evaluating Peripheral Immune Cells May Help Treat Parkinson's Disease

Long known brain disorder – Parkinson's disease may possess a close link to certain immune cells in the blood. The sleep behavioral disorder is shown to precede Parkinson's related brain changes that involve immune cells’ response in both brain and periphery as per a study at the Department of Biomedicine, Aarhus University, published in the journal PNAS. Parkinson's disease (PD) is a progressive neurodegenerative disorder that primarily affects movement due to the loss of nerve cells – neurons that produce a chemical messenger (neurotransmitter) in the brain called dopamine (black substance).

It is characterized by the hallmark formation of inclusion proteins called alpha-synuclein in the form of Lewy bodies.

Parkinson’s disease comes under a group of neurodegenerative diseases – synucleinopathies that involves both central and peripheral immune responses. And these abnormal accumulations of protein aggregates are found to be preceded by the rapid-eye-movement (REM) sleep behavior disorder (iRBD) before the onset of Parkinson’s disease.

However, the course of peripheral immune changes occurring either early or late in the disease and their relation to brain events is yet unclear.

Thus to study the prodromal phenotype of early Parkinson's disease and events occurring, the team performed a prospective case-control study to demonstrate the role of immune cells found outside the brain. That is the demonstration of monocytic markers in a cohort of iRBD patients that were associated with the brain-imaging markers of inflammation and neuronal dysfunction.

Sleep Behavior Disorder and Parkinson’s Disease

A group of patients who were suffering from REM Sleep Behavior Disorder (RBD) were included in the study. Brain scans of 15 patients with RBD and ten healthy people were done.

REM Sleep Behavior Disorder (RBD) is a condition where the patients physically act vivid dreams with vocalizations and movements. And RBD patients are associated with a high risk (90%) of developing Parkinson's or related disorders over 5-10 years.

Patients with the sleep disorder revealed inflammation with activated brain's immune cells and a loss of neuronal activity in the brain scan that directly related to changes in peripheral immune cells in the blood, the monocytes. But they had no existing symptoms of Parkinson's.

The team had found that the increased expression of immune cells – classical monocytes and mature natural killer cells in the blood of iRBD patients correlated with nigral immune activation and reduced putaminal dopaminergic function when measured with 11C-PK11195 positron emission tomography (PET) and 18F-DOPA PET respectively.

Evaluating Peripheral Immune Cells in Parkinson’s Disease

"We could see that the blood's immune system changes very early on - even before Parkinson's is diagnosed. This is the first study to show that the body's immune system continuously communicates with the brain during the development of Parkinson's disease and that changes in the body's immune system influence the condition of the neurons in the brain. In connection with Parkinson's, this presents us with new opportunities for studying the immune cells in the blood and finding new forms of treatment," says Marina Romero-Ramos, associate professor at the Department of Biomedicine at Aarhus University.

This derives a strong association between peripheral blood monocytes and brain immune and dopaminergic changes in a synucleinopathy-related disorder, thus inviting a cross-talk between periphery and brain during the disease.

Thus the study spots out the new hope to find and investigate ways to manage Parkinson's disease by treating the blood and not the brain.

"This opens up the possibility of being able to design immunotherapy that modulates cells in the blood, which subsequently would stop or delay the changes in the brain. For the patients, being able to enjoy more years with good quality of life will be very significant. It also opens up opportunities for us to be able to find biomarkers in the blood that can tell us how someone's brain is doing. Blood tests can be done more often and cheaper than a brain scan", says Romero-Ramos.

Further evaluation of the data allows it to be replicated in new groups of patients by more labs and perform more testing.

Source-Medindia